NASA Flight Research Articles

Astrobiology-Exploring the Living Universe

The new discipline of astrobiology, the study of life in the universe, addresses fundamental questions: Where did we come from? Are we alone in the universe? What is our future beyond the Earth? New capabilities in biotechnology, informatics, and space exploration provide the tools to address these questions. NASA has encouraged this new discipline by organizing workshops and technical meetings, establishing a NASA Astrobiology Institute, providing research funds to individual investigators, ensuring that astrobiology goals are incorporated in NASA flight missions, and initiating a program of public outreach and education. This paper describes the primary scientific goals of astrobiology at its inception, drawn from the NASA Astrobiology Roadmap.

Spaceflight bioreactor studies of cells and tissues

Studies of the fundamental role of gravity in the development and function of biological organisms are a central component of the human exploration of space. Microgravity affects numerous physical phenomena relevant to biological research, including the hydrostatic pressure in fluid filled vesicles, sedimentation of organelles, and buoyancy-driven convection of flow and heat. These physical phenomena can in turn directly and indirectly affect cellular morphology, metabolism, locomotion, secretion of extracellular matrix and soluble signals, and assembly into functional tissues. Studies aimed at distinguishing specific effects of gravity on biological systems require the ability to: (i) control and systematically vary gravity, e.g. by utilizing the microgravity environment of space in conjunction with an in-flight centrifuge; and (ii) maintain constant all other factors in the immediate environment, including in particular concentrations and exchange rates of biochemical species and hydrodynamic shear. The latter criteria imply the need for gravity-independent mechanisms to provide for mass transport between the cells and their environment. Available flight hardware has largely determined the experimental design and scientific objectives of spaceflight cell and tissue culture studies carried out to date. Simple culture vessels have yielded important quantitative data, and helped establish in vitro models of cell locomotion, growth and differentiation in various mammalian cell types including embryonic lung cells [6], lymphocytes [2,8], and renal cells [7,31]. Studies done using bacterial cells established the first correlations between gravity-dependent factors such as cell settling velocity and diffusional distance and the respective cell responses [12]. The development of advanced bioreactors for microgravity cell and tissue culture and for tissue engineering has benefited both research areas and provided relevant in vitro model systems for studies of astronaut well-being (loss of muscle and skeletal tissues [15-17]) and gene- and cell-level responses to the mechanical environment [13,14,18]. All five of the spaceflight bioreactor studies described above utilized three-dimensional cell culture systems in which the cells were associated with biodegradable polymer scaffolds [17], collagen gel [16], or microcarrier beads [13-15,18] in order to promote the expression of differentiated cell function. In four of the five spaceflight bioreactor studies [15-18], cells were cultured in perfused vessels (cartridges or rotating bioreactors) within recirculating loops designed to maintain medium composition within target ranges by a combination of gas exchange and fresh medium supply. Future spaceflight studies of cells and tissues are likely to involve a three-dimensional culture system, to promote cellular differentiation, and perfusion with or without rotation, to provide a gravity-independent mechanism for fluid mixing and mass transport. Previous spaceflight studies have guided the ongoing development of NASA flight hardware for the ISS (e.g. the EDU-2 and the CCU). This next generation of hardware will have extended operational capabilities including on-line microscopy, in-line sensors for the monitoring and control of metabolic parameters, modular design for replicate cultures, and, perhaps most importantly of all, compatibility with the ISS centrifuge. The latter will permit in-flight, 1 g control cultures, and thereby allow the experimental variable to be gravity itself rather than the more general "spaceflight environment". Technical limitations of spaceflight studies (e.g. allowable size, mass, and power) continue to motivate a creative approach to system design and to result in "spin-off" technologies (e.g. the STLV) for ground-based cell and tissue culture research. The increasing scientific and medical relevance of this work is evidenced by the growing number of publications in which advanced bioreactors are used for in vitro studies in physiologically relevant cell and tissue models.

Multidisciplinary Design Optimization of a Transonic Commercial Transport with Strut-Braced Wing

The multidisciplinary design optimization of a strut-braced wing (SBW) aircraft and its benefits relative to a conventional cantilever wing configuration are presented. The multidisciplinary design team is divided into aerodynamics, structures, aeroelasticity, and the synthesis of the various disciplines. The aerodynamic analysis uses simple models for induced drag, wave drag, parasite drag, and interference drag. The interference drag model is based on detailed computational fluid dynamics analyses of various wing-strut intersections. The wing structural weight is calculated using a newly developed wing bending material weight routine that accounts for the special nature of SBWs. The other components of the aircraft weight are calculated using a combination of NASA's flight optimization system and Lockheed Martin aeronautical systems formulas. The SBW and cantilever wing configurations are optimized using design optimization tools (DOT) software

Kids in space

The 81st mission in NASA's space shuttle program was the 2nd for KidSat, a program to bring space exploration down to Earth for middle and high school students. A joint program of NASA's Jet Propulsion Laboratory (JPL), the University of California at San Diego (UCSD), and the Johns Hopkins University Institute for the Academic Advancement of Youth, the KidSat program allows students to direct the operation of a camera mounted on space shuttle Atlantis.After the launch of Atlantis on January 12, a KidSat operations center (modeled after Mission Control at Johnson Space Center) went on‐line at UCSD, staffed by undergraduate and high school students. Those students receive telemetry directly from the shuttle and are able to listen to communication between NASA's flight controllers and astronauts. The KidSat operations center processes and delivers up‐to‐the‐minute information about the shuttle to 15 middle schools in the United States.

The Imaging Node for the Planetary Data System

The Planetary Data System Imaging Node maintains and distributes the archives of planetary image data acquired from NASA's flight projects with the primary goal of enabling the science community to perform image processing and analysis on the data. The Node provides direct and easy access to the digital image archives through wide distribution of the data on CD-ROM media and on-line remote-access tools by way of Internet services. The Node provides digital image processing tools and the expertise and guidance necessary to understand the image collections. The data collections, now approaching one terabyte in volume, provide a foundation for remote sensing studies for virtually all the planetary systems in our solar system (except for Pluto). The Node is responsible for restoring data sets from past missions in danger of being lost. The Node works with active flight projects to assist in the creation of their archive products and to ensure that their products and data catalogs become an integral part of the Node's data collections.

Choosing among safety improvement strategies: a discussion with example of risk assessment and multi-criteria decision approaches for NASA

This paper focuses on risk assessment and multi-criteria decision making methods applicable to deciding among candidate safety improvement strategies in the face of cost, safety and other uncertainties for NASA flight vehicles, launch vehicles and ground research facilities. Deciding on the best safety improvement strategy to implement on a spacecraft involves balancing safety with other quantifiable criteria such as technical feasibility, schedule, mass, performance, volume, and cost. The strategem of a simplified example is used to illustrate the use of probabilistic risk assessment derived results with multi-criteria decision making in the face of uncertainties. The investigated decision making approaches are intuition, cost/benefit ratio, expected impact, and Analytic Hierarchy Process. A useful sensitivity study, termed Decision Trajectories, is proposed in this paper. The example, using the shuttle auxiliary power units (APUs), is limited to the following criteria: (1) safety improvement of proposed strategies, and (2) the associated recurring and non-recurring costs. These two criteria provide sufficient richness of domain to illustrate the technologies of risk assessment and decision making. Because of the general unfamiliarity of the readers with work being conducted by NASA, this paper also provides the needed background.

Special Issue on Space Robotics

Since the beginning of space exploration, ""space robots"" have attracted the imagination of many researchers and engineers, and a number of fascinating plans for their use have been proposed.' However, only a few of these ideas have been realized in spite of the early realization that robots would be more appropriate than extra-vehicular activities by a human crew in the hostile space environment. One application is the Space Shuttle Remote Manipulator System, called the ""Canadian Robot Arm"", which has been functioning as expected for more than 10 years. In addition, ROTEX experiments on Space Lab a few years ago demonstrated that advanced robotic technology could perform more complicated tasks on board. It is also reminded that many other robotic experiments were canceled at some stage of their development: In particular, it was hoped that NASA's Flight Telerobotic Servicer would be able to operate with the help of an Orbital Maneuvering Unit. There are complicated reasons for the project cancellations, but one reason seems to be that the maturity level of robotics technology is not high enough; that advanced teleoperation and dexterous manipulation have not reached a sufficient level for practical use. In Japan, most of the space research and development thus far has concentrated on the launching and in-flight operations of conventional spacecraft, so that there has been no real demand for space robots. Recently, however, the Space Activities Committee issued a report on the long term vision for space activities in Japan. In this report, the importance of the use of space robotics technologies for diversified space activities such as space platform servicing, unmanned exploration of Mars and the moon crew support inside the space station, telescience operations, and even for the reusable reentry vehicle HOPE was emphasized. This can be at least partially attributed to the very active research on robotics in Japan, and in turn has encouraged researchers working in these fields. This special issue on space robotics introduces the research activities as several representative organizations, although it does not imply an exhaustive list. Firstly, the activities of two space development organizations are introduced. The National Space Development Agency (NASDA) is responsible for launching and operation this as well as general technology verification. Included in this is the ETS-VII satellite, which as part of its overall mission, will conduct several robotic experiments. The robotic activities of the Institute of Space and Astronautical Science (ISAS) are also outlined. This institution is primarily concerned with scientific missions to the Moon and Mars as well as planets further beyond. Second, the research activities at the national institutes are introduced. These institutes are responsible for supporting national projects at an early stage of development by providing fundamental data and key technologies. This is followed by an introduction to the very extensive research activities at universities across the country. At these universities, space robotics research is pursued not only in aerospace engineering departments but also in other disciplines such as mechanical engineering, control systems, electronics, and information processing. As mentioned before, there are some organizations which do not appear in this special issue. Nonetheless, the coordinator hopes that in Japan, the information given will prove to be useful as in introduction to space robotics research activities in Japan, and further wishes to express his deepest appreciation to all of the contributors.

Comparison of treatment strategies for Space Motion Sickness

Treatment strategies for Space Motion Sickness (SMS) were compared using the results of postflight oral debriefings. Standardized questionnaires were administered to all crewmembers immediately following Space Shuttle flights by NASA flight surgeons. Cases of SMS were graded as mild, moderate, or severe based on published criteria, and medication effectiveness was judged based on subjective reports of symptom relief. Since October 1989, medication effectiveness is reported inflight through Private Medical Conferences with the crew. A symptom matrix was analyzed for 19 crewmembers treated with oral combination of scopolamine and dextroamphetamine (scopdex) and 15 crewmembers treated with promethazine delivered by intramuscular i.m. or suppository routes. Scopdex has been given preflight as prophylaxis for SMS, but analysis showed delayed symptom presentation in 9 crewmembers or failed to prevent symptoms in 7. Only 3 crewmembers who took scopdex had no symptoms inflight. Fourteen out of 15 crewmembers treated with i.m. promethazine and 6 of 8 treated with promethazine suppositories after symptom development had immediate (within 1–2h) symptom relief and required no additional medication. There were no cases of delayed symptom presentation in the crewmembers treated with promethazine. This response is in contrast to untreated crewmembers who typically have slow symptom resolution over 72–96h. We conclude that promethazine is an effective treatment of SMS symptoms inflight. NASA policy currently recommends treating crewmembers with SMS after symptom development, and no longer recommends prophylaxis with scopdex due to delayed symptom development and apparent variable absorption of oral medications during early flight days.

Observations of diffuse resonance emissions from low‐current electron beam injections in the auroral zone ionosphere

We have observed narrowband plasma waves (≥0.1mV/m(Hz)1/2) at frequencies between the electron cyclotron frequency and the ambient plasma frequency. These waves are produced by the injection of a low‐current electron beam (>3 mA). The frequency of these emissions is consistent with the diffuse resonances that have been observed by satellite‐borne sounding experiments (Osherovich and Benson, 1991). These results were obtained from the rocket‐borne experiment SCEX 3 (Several Compatible Experiments using a rocket‐bome accelerator), NASA flight 39.002 UE, launched February 1, 1990, from Poker Flat Research Range (65.10°N, 147.50°W). These emissions are observed to propagate as far as 270 m across the ambient magnetic field with apparently little attenuation. These emissions are also observed up to 700 m from the accelerator along the electron beam.

Observations of VHF emissions from 50‐mA electron beam injections in the ionosphere that are associated with beam‐induced discharges

We have observed strong VHF plasma waves with amplitudes in excess of 0.1 mV/m (Hz)1/2 associated with 50 mA electron beam injections in the ionosphere. These observations were made up to 44 MHz, which is approximately 20 times the ambient plasma frequency. Data from three swept‐frequency receivers carried on two daughter payloads have been analyzed to determine the emission spectra of the electron beam for various energies and currents. These results were obtained from the rocket‐bome experiment SCEX 3 (Several Compatible EXperiments using a rocket‐borne accelerator), NASA flight 39.002 UE, launched February 1, 1990, from Poker Flat Research Range (65.1°N, 147.5°W). Such VHF emissions from electron beams are normally considered to be caused by a beam plasma discharge (BPD) (Llobet et al., 1985). The accelerator payload also carried photometers, which measured luminosity at wavelengths of 391.4 nm and 380.5 nm. Several times during electron gun activity the measured luminosity increased much faster than proportional to the beam current. This nonlinear increase is evidence that a discharge is occurring in the vicinity of the accelerator payload. The uniform distribution of the luminosity around the accelerator payload implies that the observed discharge extends significantly outside the beam cylinder. Because the photometers did not view the beam region directly, there is no direct evidence that a beam plasma discharge is occurring. Neutral density gauges carried on the accelerator payload and a daughter payload measured a neutral density enhanced by ∼3 orders of magnitude over model density profiles. This excessive neutral density (presumably caused by outgassing) may account for the discharge. A possible mechanism for igniting the beam plasma discharge in space is also presented.

NASA Flight Controllers Become AI Pioneers

NASA Flight Controllers Become AI Pioneers

The NASREM robot control system standard

The problem of robot control is approached from a systems standpoint where a complete control system must include all of the aspects involved in moving a robot, not just the algorithms in the classic controls literature. The NASA/NBS Standard Reference Model for Telerobot Control System Architecture (NASREM) provides the framework for a complete manipulator control system. It is composed of three hierarchies: task decomposition, world modeling, and sensory processing. The task decomposition hierarchy divides the task into smaller substasks. In order to achieve the desired decomposition, the task decomposition hierarchy must often access information stored in the world modeling hierarchy, which contains a workspace representation, object descriptions, robot models, etc. The sensory processing hierarchu constantly fills the world model with processed sensor information. The NASREM functional architecture was developed for NASA's Flight Telerobotic Servicer, a two-armed robot which will build and maintain the Space Station. However, the control concepts proposed by the NASREM functional architecture immediately transfer to other applications such as in manufacturing, autonomous vehicles, etc.

Space construction results: The EASE/ACCESS flight experiment

This paper describes NASA ground and flight test activities in the development of in-space construction techniques for the assembly of Space-Station-sized structures. In November 1985, the first experiments on space construction using EVA astronauts were flown aboard the Space Shuttle, with spectacular and highly visible results. The EASE and ACCESS flight experiments are described and the ground and water tank test program and operations in-flight including instrumentation are presented, together with illustrations of assembly and disassembly of both the EASE and ACCESS experiments. The flight test results are presented and learning and productivity curves are discussed, with differences between free EVA vs EVA using foot restraints compared. Two weeks after the flights, the Space Station structural assembly technique was selected to be EVA astronaut assembly of the truss, based on the flight experiment results.

Ion beam releases at rocket altitudes

NASA Flight 29.015 was the third in a series of flights to study the electrodynamics of man-produced ion beams in the ionosphere. Much like an earlier flight, plasma releases perpendicular to the earth's B field result in ions being measured, often at reduced energies, several hundred meters from the source along the magnetic field. Releases at 200 eV energy parallel to B , however, result in > 200 eV ions measured above the source. In addition, parallel ion releases result in two additional populations of ions seen near 90° pitch angle; one near the energy of the generator, and the other at considerably lower energy. The energization of parallel ions could result from the same process by which electrons were accelerated to the generator payload as measured on an earlier flight, presumably due to blockage of natural field-aligned currents by gun-related wave turbulence. This turbulence is also undoubtedly inherent in the mechanism by which a parallel beam of ions creates a perpendicular component.

NASA aerospace flight battery system program plan

The objective of the NASA flight system program is to provide NASA with a policy and posture which will increase the safety, performance and reliability of space power systems. This will be accomplished through better control over battery system integration and improved performance, safety, and quality of primary and secondary cells and batteries. All NASA centers will be involved according to their expertise, resulting in a unified, coordinated effort for future problem avoidance and improved performance, safety, and reliability.

Civil Helicopter Flight Operations Using Differential GPS

The results of NASA flight trials of a dual-receiver differential global positioning system (DGPS) for civilian helicopter navigation applications, are presented. The three principal components of the DGPS system are described, including the GPS ground-reference system, a range tracking system, and an on-board sequential GPS receiver. The ground-based receiver in the DGPS operates at a known fixed location and receives C/A code signals from NAVSTAR satellites. System bias errors in the ground receiver are subtracted from the airborne solution for the navigational fix. Calculations of the differential bias error are carried out using an on-board PDP-11/34 M research computer. The ground-reference differential corrections for satellites are given in a table. It is shown that the differential correction signal of the DGPS contains only a small (0.1 rad/sec) high-frequency component which can be attributed to system error. A schematic diagram of the DGPS postflight data processing routine is provided.

New Shape in the Sky

Currently undergoing NASA flight testing is the Grumman X‐29 forward swept wing (FSW) demonstrator aircraft which was built under a contract sponsored by the Defence Advanced Research Projects Agency (DARPA) and funded through the Air Force. The FSW aircraft first took to the air in December, 1984 and after four flights with the manufacturer was handed over to NASA for a verification programme involving all the benefits of this design. Advanced technology features which will be demonstrated are the forward swept wing for improved aerodynamic efficiency and good control at high angles of attack; tailored composite wing structure that resists the tendency towards structural divergence inherent in this configuration; thin supercritical aerofoil for improved transonic performance at high lift coefficients; variable camber trailing edge to reduce drag at all lift coefficients and avoid supersonic drag associated with aerofoil camber; canard longitudinal control for efficient trimming of variable camber pitching moments and favourable canard‐wing interactions; highly relaxed static stability for very low trim drag at all Mach numbers; and a digital fly‐by‐wire flight control system.

Acceleration of electrons in strong beam‐plasma interactions

The sounding rocket payload SCEX (Several Compatible Experiments to utilize an electron accelerator; NASA flight 27.045) launched on January 27, 1982 from the Churchill Research Range provided an opportunity to observe the effects of strong beam‐plasma interactions on the electron population in a region of space remote from the main payload carrying the accelerator. We present observations demonstrating that electron energies of up to four times the injection energy occurred during accelerator operations in high‐current mode. Detailed instrumental performance characteristics in flight and in the laboratory will be discussed. The acceleration events occurred at reception pitch angles between 54° and 126°. Long confinement times seem to be a necessary condition for generating the energetic electrons. It is proposed that they result from the length of the interaction region.

Miniature triaxial metastable ionization detector for gas chromatographic trace analysis of extraterrestrial volatiles.

Gas chromatography has found highly successful application in NASA's flight programs. Gas chromatographs have been flown to both Mars and Venus where detailed compositional measurements were made. These instruments were quite small and relatively sensitive when compared to commercially available instruments; however, they do not appear adequate for future missions currently being planned. The earlier flight GC's had incorporated thermistor bead thermal conductivity cells as the detector. This detector requires very precise temperature control and only provides about 1 ppm sensitivity. Temperature stabilization causes the detector to be quite heavy, i.e., about 200 g. Greater sensitivity will be required for measurements of trace components in extraterrestrial environments. Review of other detector types revealed the metastable ionization detector as a likely candidate because of its superior thermal stability and high sensitivity. The metastable detector, first described by Lovelock as an argon ionization detector, has been studied and somewhat modified by others. The commercial design by Hartmann and Dimick was used for comparison purposes in our work. In the past, three features of the metastable detector are prominent: it has part-per-billion sensitivity, contamination must be carefully controlled, and anomalous response is common. Since it is an ionization detector, however, temperature instabilities do not cause the major perturbations experienced by the thermal conductivity detectors. This paper describes a miniature metastable ionization detector featuring an unconventional electrode configuration, whose performance characteristics parallel those of traditional design, while its weight is quite small. The prototype has been used in our laboratories routinely for 2 years, and the concept will be incorporated into a flight GC for use in the Space Shuttle.

Effects of Aircraft Motion on Passengers' Comfort Ratings and Response Times

Comfort ratings and response times for changes in the experienced level of comfort were examined in 20 subjects using the NASA Flight Research Center's Jetstar aircraft modified to carry the GPAS system (General Purpose Airborne Simulator). Data were obtained for each of the subjects during two runs of 10 1-min. flight segments. In general, as the magnitude of aircraft motion increased in either the vertical or transverse (lateral) directions, there was an increase in feelings of discomfort and a decrease in response times to those changes. These results suggest parallels between the large body of laboratory data on human reaction time and that collected in this field study on response times to changes in ride comfort.